Global Variables
To access an internal PHP global variable from a function in your extension, you first have to determine what kind of global variable it is. There are three main types: SAPI globals, executor globals, and extension globals.
SAPI Globals (SG)
SAPI is the Server Abstraction API. It
contains any
variables
related to the web server under which PHP is running. Note that not
all SAPI modules are related to web servers. The command-line version
of PHP, for example, uses the CGI SAPI layer. There is also a Java
SAPI module. You can check which SAPI module you are running under by
including SAPI.h
and then checking
sapi_module.name
:
#include <SAPI.h> /* then in a function */ printf("the SAPI module is %s\n", sapi_module.name);
See the
sapi_globals_struct
in the main/SAPI.h
file for a list of available
SAPI globals. For example, to access the
default_mimetype
SAPI global, you would use:
SG(default_mimetype)
Some elements of the SAPI globals structure are themselves structures
with fields. For example, to access the
request_uri
, use:
SG(request_info).request_uri
Executor Globals (EG)
These are runtime globals defined
internally by the Zend executor. The most common EG variables are
symbol_table
(which holds the main symbol table)
and active_symbol_table
(which holds the currently
visible symbols).
For example, to see if the user-space $foo
variable has been set, you could do:
zval **tmp; if(zend_hash_find(&EG(symbol_table), "foo", sizeof("foo"), (void **)&tmp) == SUCCESS) ...
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